UNDERSTANDING ELECTRICS

We'll start this chapter on Electrics with a brief overview of good practice when considering the electrical systems on your canal boat.

Here is a brief definition of some of the terms we refer to within the Electrics section:

Amps
This is a unit of electric current. It is a physical count of how many electrons are flowing down a cable. Amps cannot be lost or damaged, for example if 5 amps left a battery; 5 amps would return to the battery

Volts
This is the 'push' to force the electrons to flow around the wires. It's this push that gets used up when electricity does work, so whenever work is done the voltage gets used up or drops. Voltage drop can be an issue on canal boats and narrowboats.

Watts
This is the most common measurement used on domestic appliances and most readily available on product descriptions and packaging, for example a 2000 watts hairdryer or 750 watts microwave will describe how hot a microwave will be. It is important to understand the wattage of any appliances you wish to use on board a canal boat or narrowboat and whether your power system can support it.

Volts, amps and watts are linked by the following formula:
Watts = Volts x Amps or
Watts divided by Volts = Amps
If something reduces the voltage, typically volt drop, less current will flow so less electrical power is available and appliances may not work to their full potential.

DC and AC
Electrical current from batteries and alternators always flows postive to negative by convention. In AC (alternating current) the current flow constantly reverses direction. This enables hig voltages to be sent longer distances. This is the basis for domestic electricity supply.

OHMS
This is a measure of resistence, therefore restricts current flow. For example a low wattage bulb will only allow a small current flow.

Amp Hour
This indicates how much electricity a battery will hold. A 110 ah (amp hour) battery is theoretically capable of supplying 110 amps for one hour.

The most important things to understand about electricity are that unless you respect it, can cause fire or even kill you.

We expect all users of The FitOutPontoon will be sensible, level headed individuals so please excuse us for pointing out the obvious.

We also appreciate that a little knowledge can be a dangerous thing and the benefit of a professional will be that it is their livelihood that is at stake if they get it wrong.
We do cover some theory in this site, and where possible we will give guidance based on sound principles. For example, we explain how to correctly size wiring and to work out current loads. Aside from that, we recommend your electrical work is entrusted to the most competent person you can find.

That may be you, so if you’re not a qualified marine electrician there are some very good basic electrical courses available that are specifically aimed at the canal boat market. Anyone who has a passing interest in the subject could do a lot worse than enrolling on a day or two course.
A good course will teach you by classroom theory as well as practical application. You will learn not only about DC circuits for the leisure system but also about DC in the engine room.

Unfortunately, many older boats suffer from poor quality fiddling, where accessories have been added to wiring systems that are barely able to cope. The biggest problem with canal boat electrics are that they are for the most part hidden away behind panelling.

Your Boat Safety Examiner or Marine Surveyor will be able to advise those of you contemplating a new purchase whether or not he/she feels there is anything that could be improved for the future.

If you are having a new boat built, you shouldn’t have any concerns. Just ask your builder to try and make things accessible for when something breaks in the future!

Always ensure your or others work conforms to the Boat Safety Scheme and Recreational Craft Directive.

When designing your electrical circuit it is good practise to keep a set of diagrams of the cable runs, relating everything to the gauge of the wiring, fuse capacities, function etc etc.
In the future, it will be a lot easier to trace faults and add to the system. In fact it’s probably the only way to safely work out and plan the current carrying capacity of the individual circuits.
Make separated records and flow charts for DC and AC systems to avoid confusion. Keep these with your boat records for easy access.

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